Transhydrogenase-2 Activity Assay kit

TH is located on the inner membrane of mitochondria, also known as mitochondrial complex VI. It catalyzes the mutual conversion of NADH+NADP+ and NAD++NADPH, and regulates the balance of mitochondrial NAD(H) and NADP(H). The reverse reaction is called TH-2, which catalyzes NADPH and NAD+ to produce NADP+ and NADH.

NADH and NADPH both have characteristic absorption at 340nm, so the hydrogen transfer reaction catalyzed by TH cannot cause a change in absorbance at 340nm. Using the synthetic substrate 3-acetylpyridine adenine dinucleotide (APAD+) instead of NAD+, TH-2 catalyzes the reduction of APAD+ to APADH. APADH has a characteristic light absorption at 375nm. The increase rate of light absorption at 375nm is measured to calculate TH- 2 Activity.